Physics Profile: Dalit Engelhardt

Undergraduates usually aren’t involved in research on the most fundamental properties of matter at the highest energy scales, but alum Dalit Engelhardt was.

Dalit studied how exotic, long-lived particles can be detected at the Large Hadron Collider (LHC) at CERN. Physicists have a working model of elementary particles, called the Standard Model, that has been tested and re-tested over the past three decades – each time with new, more precise measurements or at higher energy scales. The problem is that the Standard Model doesn’t explain many basic things, such as the origin of mass, the unification of all forces, or the way the forces we now observe at low energy were created out of unified forces at high energy. For these reasons, particle physicists have developed a variety of new models beyond the Standard Model.

Under the guidance of Professors Steve Ahlen and Kenneth Lane, Dalit examined ways to detect some of the stranger new particles that these models predict, like particles that are not only very massive and long-lived but are also doubly-charged. Some models of technicolor and supersymmetry predict these exotic particles. They can also be part of a composite, dark matter particle: Instead of having one elementary particle as the mysterious dark matter that is abundant in the universe, it is possible to have a composite neutral state of two oppositely-charged particles. In a collider, we might observe the separate elementary components.

Dalit’s research examined the possible signatures of these particles at the LHC. Because they are long-lived, they can reach the outmost layers of the detectors just like muons. But unlike muons, they are much heavier and move more slowly. They also lose a lot of energy in the detector. As a result, they are much trickier to trigger on and to reconstruct correctly; because they have small production rates in the first place, they can easily be missed altogether. Understanding these signatures is therefore a key step toward identifying, rejecting or placing bounds on theories beyond the Standard Model and, consequently, gaining insight into physics at very high energy scales.

Occasionally, Dalit finds herself pursuing interests not involving unusual speeding particles. For as long as she can remember, she has enjoyed writing historical fiction and has taken an interest in folklore and mythology. She used to spend many hours perusing anthologies of legends from all over the world, and they still serve as her inspiration for writing and traveling.

Dalit is also an avid traveler, having hiked in over 25 national parks in the U.S. and Canada and journeyed abroad to many locations, including Ireland, France, Israel, Mexico, England, Austria and Spain. And this year, she’s headed for the UK again to pursue graduate studies. She enjoys outdoor activities and nature, especially hiking, biking, kayaking and skiing. That means no season is an indoor season for her – even in New England.